The GPRS/UMTS is an evolution of the global system for mobile communications (GSM) standard to provide packet switched data services to GSM mobile stations. Packet-switched data services are used for transmitting chunks of data or for data transfers of an intermittent or bursty nature. Typical applications for 3GPP packet service include Internet browsing, wireless e-mail, and credit card processing, etc.
FIG. 1A is a block diagram illustrating typical 3GPP packet architecture. Referring to FIG. 1A, user equipment (UE) 101 is communicatively coupled to a radio network controller (RNC) 102 of a radio access network (RAN) 103. In order to access other networks such as Internet 107 and/or operator services node 108, UE 101 has to go through 3GPP packet core network 106. Typically, 3GPP packet core network 106 includes a serving GPRS support node (SGSN) 104 and a gateway GPRS support node (GGSN) 105. These support node SGSN and gateway node GGSN relay communications between a user terminal (e.g., source mobile station) and a destination.
Note that typically, there may be multiple SGSNs associated with a GGSN, multiple RNCs associated with a SGSN, and multiple UEs associated with an RNC in a hierarchical structure (not shown). Thus, when traffic from the UEs increases, the traffic imposed on higher level nodes (e.g., SGSN and/or GGSN) in the hierarchical structure will be exponentially increased.
As the adoption of mobile broadband increases, the need for higher capacity backhaul and higher capacity in processing nodes goes up. Evolved high speed packet access (HSPA+) provides a bandwidth in tens of mbps per user and adding femto services to the 3G offering will encourage users to consume and generate more mobile broadband traffic. That in turn may choke the core network nodes which were not designed for the onslaught of the mobile broadband. There have been some discussions in the industry to offload the 3GPP packet core networks from heavy Internet bound broadband traffic, for example, by introducing a mobile data offload gateway (MDO-GW) device, which reroutes Internet bound traffic directly to Internet, bypassing the core network such as SGSN.
While there are many ways to offload the core network, most of them involve re-configuration or restarting of existing nodes (e.g., RNC, SGSN) in the network, which increases the operational cost for the mobile operators as well as disrupts services from the user perspective. For example, if an MDO-GW device is introduce between RNC 102 and SGSN 104, the RNC 102 and SGSN 104 have to be reconfigured and an existing communications session has to be terminated.
As more operators and transport network providers are moving to Internet protocol (IP) networking for all their infrastructure needs, the interface (e.g., lu-ps) between RNC 102 and SGSN 104 has either been or is in process of being upgraded to signaling transport (SIGTRAN) based transport layers. Even in a legacy asynchronous transmission mode (ATM) based network, SIGTRAN can selectively be introduced by using ATM or IP converters.
FIG. 1B is a block diagram illustrating a SIGTRAN-based protocol stack for a packet domain. As shown in FIG. 1B, the stream control transmission protocol (SCTP) layer establishes a connection between RNC 102 and SGSN 104 to provide reliable communication between the two. The IP address and the port identify a peer entity. The media transfer protocol (MTP) level 3 (MTP3) user adaptation (M3UA) layer is a counterpart of signaling system #7 (SS7) MTP3 for SIGTRAN and provides a connectionless association between RNC 102 and SGSN 104. The signal connection control point (SCCP) layer provides a connection per session to carry RAN application part (RANAP) messages. There could be as many SCCP connections as the number of sessions between RNC 102 and SGSN 104.
In order to insert a new node such as an MDO-GW between RNC 102 and SGSN 104, each of these protocol layers has to be reconfigured and an existing connection between the corresponding protocol layers of RNC 102 and SGSN 104 have to be terminated and restarted. This may cause unnecessary disruptions to the operations of RNC 102 and SGSN 104.